Measurement of χc1 and χc2 production with √s = 7 TeV pp collisions at ATLAS

Journal

The Journal of High Energy Physics

Volume | Issue number

2014 | 07

Article number

154

Number of pages

51

Document type

Article

Faculty

Faculty of Science (FNWI)

Institute

Institute for High Energy Physics (IHEF)

Abstract

The prompt and non-prompt production cross-sections for the χc1 and χc2 charmonium states are measured in pp collisions at
√s = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χc states are reconstructed through
the radiative decay χc → J/ψγ (with J/ψ → μ+ μ−) where photons are reconstructed from γ → e+ e− conversions. The production
rate of the χc2 state relative to the χc1 state is measured for prompt and non-prompt χc as a function of J/ψ transverse momentum.
The prompt χc cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt
J/ψ produced in feed-down from χc decays. The fractions of χc1 and χc2 produced in b-hadron decays are also measured.

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